Generally oil and mechanical seals are used for sealing sliding contact section. It is, however, very difficult to seal a propellant, e.g. compressed or liquefied gas, with the oil or mechanical seal.
For example, in the case of an aerosol container as disclosed in Japan Utility Publication No. 1,474/70, a movable piston means is placed therein to separate the liquefied gas area from the product area. When the piston means slides within the container, the liquefied propellant gas leaks into the product area from the sliding contact section, i.e. from the narrow gap between the piston means and the inside wall of the container. In order to stop such leakage, silicon gum has been used as sealant. The use of silicon gum, however, results in an insufficient seal, and has an additional demerit that the silicon gum per se does not tolerate long use due to rapid deterioration. In order to overcome such disadvantages of the prior art, the present inventors applied for patent a sealing composition for sliding contact section wherein a polyol is used (Japan Patent Kokai No. 213,076/83).